Microtomes for sectioning frozen or cooled specimens comprise a special cooling device. The samples to be sectioned are cooled, in this context, to a specific predetermined temperature. The temperatures are as a rule between −10° C. and −50° C. To ensure a constant temperature, either the microtomes are arranged in complexly encapsulated cryostat chambers and the latter are appropriately cooled, or separate refrigeration devices are provided that can be attached to the microtome. A microtome having a cryostat chamber and a refrigeration device is presented, for example, in DE 44 34 937 C1 and its counterpart U.S. Pat. No. 5,711,200. In this document, the entire cryostat chamber is cooled by way of the refrigeration device.
A temperature regulating device for the specimen receptacle in a cryostat microtome is disclosed in DE 94 21 559 U1. Associated with the specimen receptacle is a specimen head on which the specimen to be sectioned can be mounted. The specimen receptacle is equipped with cooling hoses for cooling the specimen head and the specimen.
The company document “LEITZ 1512 Rotationsmikrotom, Anleitung, Liste [Rotary microtome, instructions, list] 311.530-047, April 1981, Ernst Leitz Wetzlar GmbH” discloses a microtome (Leitz 1512) having an attachable, separate “Kryomat 1700” cooling unit. Here a freezing chamber having a coolant connector hose is mounted in the specimen clamp of the microtome. The specimen stages with the samples are slid onto the freezing chamber and cooled there.
The above-described devices for sectioning cooled or frozen samples have proven successful in practical use.
With very thick specimens or specimens embedded in paraffin, however, it has been found that the heat generated by the sectioning operation at the surface of the specimen cannot be dissipated quickly enough. The result is that the sample begins to thaw in the region of the sectioned surface, and the sectioning temperature is thus no longer optimal. For this reason, in practical use the specimens are removed from the specimen receptacle and brought back to the requisite temperature on separate cooling plates. This procedure is of course very time-consuming, since each specimen change necessitates a realignment of the specimen with respect to the knife edge.